This invention relates to an improved fluid logic device and more particularly to an improved construction for a fluid logic flip-flop device.
Fluid logic devices for control of industrial equipment have become increasingly useful recently. Utilization of such devices with pneumatic and hydraulic equipment may eliminate the need for electrical control, thereby eliminating the potential hazard of electric shock and spark. Bouteille in his book "Fluid Logic Controls and Industrial Automation", John Wiley and Sons, 1973, reviews the state of the art of fluid logic control devices. In the Bouteille book, numerous types of logic devices are disclosed including AND, OR or NOT logic devices. Additionally, a so-called memory device is disclosed. The memory device is also known as a "flip-flop" device.
The so-called flip-flop device provides an output signal in response to a pulse or a constant input signal. In other words, the output remains in the "on" state once it has been triggered by an appropriate input signal. The output remains constant even though the input is subsequently turned "off". A positive cancellation signal is required in order to shift the output signal to the "off" position.
Various structures have been developed to provide the flip-flop function. Many of these structures are illustrated in the Bouteille reference. Generally, these structures provide a poppet or sliding D valve mounted in an elongated bore. FIGS. 3-29, 3-30 and 3-31 of the Bouteille reference illustrate various typical embodiments of prior art structures.
While such prior art structures function well, they are often expensive to make. Additionally, the sliding valve members in prior art flip-flop devices are subject to wear. Relatively low shifting pressures compared to supply pressure may result in false signaling. Often, such prior art devices do not have a quick, sharp, snap action feature. Finally, prior art devices often require precise machining operations during manufacture. This may add significantly to the manufacturing cost of the product.